Accelerometry data from the National Health and Nutrition Examination Study (NHANES) confirms what has been suspected from self-report: after adolescence, people in the United States are very inactive. With age, even this modest activity declines further. To better explore the association of physical activity and inactivity with conditions and outcomes of aging, accelerometry data was collected on a subsample of participants from the Health, Aging, and Body Composition study in the year 10 and year 16 clinical examinations. We are working with this data to study the paterns of true daily activity in older adults. Additionally, we collected accelerometry and sleep data in a subsample of participants from the Age, Gene/Environment Susceptibility Study in Iceland. Also, as part of this project, we compare measurements from accelerometers worn at various locations on the body while eldery participants conduct activities of daily living. Current expansion of this project will include objective activity monitoring in a free-living environment in older adults who have undergone surgery, are part of a clinical trial, or are undergoing a major life change such as transitioning to retirement.